AI Representation: In Wyoming, an automated camera system spotted approaching eagles and stopped turbines. Image credits: Wikimedia Commons
In a 2021 study published in the Journal of Applied Ecology, Christopher J. Lastly, 7 of 42 reported eagle fatalities were left out of the analysis and the reason was unclear. With these corrections in mind, the USGS note provides an estimate of a 50% reduction with an interval from -159% to 89%, a range that includes no reduction or even an increase.
Because it assumed the deviation at the neighboring site would also apply to the treatment site, and it varied depending on the arbitrary date used to divide the before and after periods, the effect size was exaggerated. Wind power and eagles both depend on open, windy land. Large raptors such as golden eagles use steady winds and rising air currents to travel and hunt with little effort and wind developers site turbines on ridges and plains for the same conditions. This spatial overlap places eagles within range of the moving blades and has long complicated wildlife management and turbine permitting operations. Operators either shut down turbines temporarily or slow them when birds are detected, generally with the help of on-site human observers. Observers could monitor only a limited number of turbines and could not remain active all day. This prompted research into whether cameras and software could do the job without human direction. A case study conducted in Wyoming tested this idea. The Peregrine Fund describes IdentiFlight as a combination of camera and machine learning technology that detects flying objects, classifies them and shuts down the turbine if an eagle is threatened with impact. W. McClure, Brian W. Rolek, Leah Dunn, Jennifer D. McCabe, Luke Martinson and Todd E. There were four problems that Huso and Dalthorp found with this data. First, the original study compared the mean of four years before activation with just one year after, without controlling for year-to-year variation. Also, there was only one treatment year at one location, which is insufficient to establish a causal effect.
The above-mentioned study found that estimated eagle fatalities at the treatment site declined by 63% between the periods before and after automated curtailment was introduced, while fatalities at the control site increased by 113%. The January 2021 before-after-control-impact study The findings were published on January 20, 2021, in the Journal of Applied Ecology in a paper titled Eagle fatalities are reduced by automated curtailment of wind turbines, available through the US Geological Survey (USGS) publication page. They compared eagle fatality rates at Top of the World with those at a control location 15 km away, which lacked automated curtailment, both before and after the implementation of the automated system. A later 2023 paper in the Journal of Applied Ecology , Reanalysis indicates little evidence of reduction in eagle mortality rate by automated curtailment of wind turbines, was written by USGS scientists Manuela Huso and Daniel Dalthorp.
Because eagle abundance and weather conditions change annually, a control location is important. Katzner evaluated an automated camera system designed to detect approaching eagles and stop wind turbines at the Top of the World Windpower facility in Wyoming. The researchers compared eagle fatalities at the facility with those at a nearby control site. The researchers used a before-after-control-impact experimental design. The reanalysis examined the same treatment site over roughly four years before IdentiFlight was installed and only about six months to one year afterwards, alongside a control site and argued that the data do not support a clear change in underlying mortality rate. The authors concluded that the effect estimate was too imprecise to rule out either a decrease or an increase.
